Standard No.:	GB 12009.4-1989
English Name:	Polymethylene polyphenyl isocyanate-Determination of isocyanato content
Chinese Name:	多亚甲基多苯基异氰酸酯中异氰酸根含量测定方法
Chinese Classification:	G31    Basic standards and general methods for synthetic resin and plastic
Professional Classification:	GB    National Standard
Source Content Issued by:	China Petroleum and Chemical Industry Federation
Issued on:	1989-12-25
Implemented on:	1990-11-1
Status:	superseded
Superseded by:	GB/T 12009.4-2016 Plastics―Aromatic isocyanates for use in the production of polyurethane―Part 4:Determination of isocyanate content
Superseded on:	2016-9-1
Abolished on:	2016-09-01
Target Language:	English
File Format:	PDF
Word Count:	1500 words
Translation Price(USD):	45.0
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Polymethylene polyphenyl isocyanate - Determination of isocyanato content 1 Subject content and applicable scope This standard specifies two methods for determining the isocyanato content in polymethylene polyphenyl isocyanate by potentiometric titration. It is applicable to the determination of isocyanato content in polymethylene polyphenyl isocyanate for polyurethane foam. 2 Normative references GB 601 Chemical reagent - Preparations of standard volumetric solutions 3 Method A 3.1 Principle Isocyanate reacts with dibutylamine to produce urea, and excessive dibutylamine is subjected to potentiometric titration with hydrochloric acid standard solution to determine the isocyanato content. 3.2 Reagents In the analytical method, analytically pure reagent and distilled water or water of equivalent purity shall be used. 3.2.1 Toluene (GB 684): dehydrated by 4A molecular sieve. 3.2.2 Isopropanol. 3.2.3 c[NHC(C4H9)2]＝2mol/L dibutylamine toluene solution: weigh 260g of dibutylamine in a 1,000mL volumetric flask, dissolve it with toluene dehydrated by 4A molecular sieve and dilute to the scale. 3.2.4 Hydrochloric acid standard solution: c(HCl)＝1mol/L, prepared and calibrated according to GB 601, 4.2. 3.3 Apparatus

1 Subject content and applicable scope 2 Normative references 3 Method A 4 Method B 5 Calculation and representation of results 6 Tolerance 7 Test report 8 Arbitration method Additional explanation